Designing high-order power-source synchronous current converters for islanded and grid-connected microgrids

This paper deals with development of a versatile and compact control strategy for voltage source converters in grid-connected and islanded microgrids using synchronous current converters technology. The key feature is its new integrated high-order controller/synchronizer with applicability to both operational modes without strategy rearrangement. Using high-order controllers, on the other hand, results in rather complex analysis and design process, therefore this paper aims at providing a general and simple theme for the design and parameter selection. The controller also provides adaptive and automated current-based grid synchronization. Moreover, the controller realizes a power-source current-controlled microgrid with minimum control loops, as compared to widely adopted voltage controlled microgrids in the literature, with advantages such as fault-ride-through and inherent droop-less power sharing capabilities. Adaptive current-based synchronization and smooth switching to islanding mode provides high flexibility, reliability and only-plug operation capability. Extensive simulation and experimental results are presented to demonstrate performance of the proposed control and management strategy.